1. Field of the Invention
The present invention relates to a digital signal processor having a volatile program memory.
2. Description of the Related Art
A digital signal processor (DSP) is a type of computing device that is similar to a-microprocessor but has specialized features adapted for signal processing. In particular, a DSP has a hardware multiplier that can multiply at high speed while an addition computation is performed concurrently. This enables multiply-and-accumulate operations, which are common in digital signal processing, to be carried out in real time.
A volatile program memory such as a random-access memory (RAM) enables a DSP to download and then execute programs that implement a variety of processing functions. In a mobile telephone, for example, these functions may include user interface functions related to a keypad and display, functions for reproduction of music, or functions enabling the DSP to operate as a Java virtual machine (Java is a registered trademark denoting a programming language). Some of the necessary program code may also be stored in a non-volatile program memory such as a read-only memory (ROM).
While downloading a program into a volatile program memory, a conventional DSP remains in a standby state. Execution of the program cannot begin until the entire program has been downloaded, which may take some time. Even then, execution of the program may not produce immediately audible or visible results, because in many programs an initialization sequence has to be executed before the actual signal processing can begin.